JPS63273221A - Information processor - Google Patents

Abstract

PURPOSE:To perform stable and accurate control, by focusing a beam of light from a light source on a recording medium, and performing gain amplification in which a detecting signal from reflected light is selected by a digital signal corresponding to the status of the recording and reproduction of information. CONSTITUTION:The beam of light from the light source 14 is focused on an optical disk 1 by an optical head 10, and the reflected light is converted to an electrical signal by an optical detector 16. The outputs of optical detecting cells 16a and 16b are supplied to a subtraction circuit 22 via amplifier circuits 20 and 21, and the output is supplied to a selector 24 via resistors R0-R7 with different resistance values. The selector 24 selects the resistor corresponding to the digital signal from an FF circuit 25 responded to the status of the recording and the reproduction, and the output is amplified at a gain control amplifier 27. And the output of the amplifier 27 is supplied to a driving circuit 28 as a track deviation detecting signal, thereby, tracking deviation is corrected. In such a way, it is possible to perform the stable and accurate control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an information processing device such as an optical disk device that records or reproduces information on an optical disk using, for example, focused light.

(Prior Art) In recent years, image information such as documents, which are generated in large quantities, is photoelectrically converted by two-dimensional optical scanning, and this photoelectrically converted image information is recorded on an image recording device, or it can be used as needed. Recently, optical disk devices (information processing devices) have been used as image recording devices in image information file devices that can search, reproduce, and reproduce and output as hard copies or soft copies.

Conventionally, such optical disk devices have used optical disks that record information in a spiral manner.
Information is recorded or reproduced by an optical head that is moved linearly in the radial direction of the disk by a linear motor.

In such a device, when tracking the objective lens in the optical head, the beam may not be irradiated at an appropriate position due to mounting errors or the like. Therefore, by taking the difference between the two types of detection signals for tracking and passing a current corresponding to the signal difference to the objective lens driving coil,
The objective lens is driven to the correct track position.

That is, the semiconductor laser beam is focused onto the recording medium by a condensing lens, and its reflected light enters a two-split detector, and tracking control is performed so that the output difference between them becomes zero.

In an optical disk device, the laser beam output is large during recording, so the incident light on the two photodetectors is also large, so regardless of the size of the incident light on the two detectors,
An analog divider (normalization) is used to keep the loop gain of the control circuit constant and stabilize the servo system.

However, in the above-mentioned devices, analog dividers were used, but they were very expensive, had poor division accuracy, and
In particular, it has the disadvantage that an offset voltage occurs in the output due to changes in temperature or the size of the denominator of the division, and the offset voltage is added to operate the servo, making it impossible to perform accurate tracking.

Furthermore, for the same reason, it also has the disadvantage that accurate focusing cannot be performed.

(Problems to be Solved by the Invention) The present invention eliminates the drawback that the focusing means cannot be controlled stably and accurately. The purpose is to provide an information processing device that can perform the following steps.

[Structure of the Invention] (Means for Solving the Problems) An information processing device of the present invention includes a focusing means for focusing light emitted from a light source onto a recording medium, and a focusing means for focusing light emitted from a light source onto a recording medium. detection means for detecting the first and second signals;
an output means for outputting a digital signal corresponding to the recording or reproduction of information on the recording medium; a selection means for selecting a gain corresponding to the digital signal outputted by the output means; 1. Calculating means for obtaining a signal for controlling the focusing means by subtracting the second detection signal; amplifying means for amplifying the signal obtained by the first calculating means with a gain selected by the selecting means; It is comprised of a driving means for driving the focusing means with a signal amplified by the amplifying means.

(Operation) The present invention focuses light emitted from a light source onto a recording medium using a converging means, detects first and second signals from the light from the recording medium, and detects the first and second signals from the light from the recording medium. By outputting a digital signal corresponding to the recording or reproduction of information, selecting a gain corresponding to the output digital signal, and subtracting the first and second detection signals detected above, the above-mentioned obtaining a signal controlling the focusing means;
This obtained signal is amplified with a selected gain, and the amplified signal drives the focusing means.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an information processing device, such as an optical disk device, according to the present invention. That is, an optical disk (recording medium) 1 is moved by an optical head 10 by a motor 2.
In contrast, it is designed to be rotated at a constant linear velocity. The optical disc 1 has a donut-shaped metal coating layer such as tellurium or bismuth coated on the surface of a circular substrate made of glass or plastic, for example.

An optical head 10 for recording and reproducing information is provided on the back side of the optical disc 1.

This optical head 10 is constructed as follows.

That is, 14 is a semiconductor laser (light source), and this semiconductor laser 14 generates a diverging laser beam.

In this case, when writing (recording) information onto the recording film of the optical disc 1, a laser beam whose light intensity is modulated according to the information to be written is generated, and the information is read from the recording film of the optical disc 1 (reproducing). In some cases, laser light is generated with a constant light intensity.

The diverging laser beam generated by the semiconductor laser 14 is converted into a parallel beam by the collimator lens 13 and guided to the polarizing beam splitter 12. The laser beam guided to this polarizing beam splitter 12 is reflected by this polarizing beam splitter 12, enters an objective lens (focusing means) 111, and is focused by this objective lens 11 toward the recording film of the optical disc 1. .

Here, the objective lens 11 is supported movably in the direction of its optical axis and in the direction orthogonal to the optical axis, and when the objective lens 11 is positioned at a predetermined position, the focused light emitted from the objective lens 11 is The beam waist of the optical laser beam is projected onto the surface of the recording film of the optical disc 1, and a minimum beam spot is formed on the surface of the recording film of the optical disc 1.

In this state, the objective lens 11 is maintained in a focused state and a focused track state, and information can be written and read.

Further, the diverging laser beam reflected from the recording film of the optical disk 1 is converted into a parallel beam by the objective lens 11 when focused, and is returned to the polarizing beam splitter 12 again. This laser light passes through a polarizing beam splitter 12 and is irradiated onto a photodetector (detection means) 16 by a projection ηj lens 15.

This photodetector 16 includes photodetection cells 16a, 1 that convert the light imaged by the projection lens 15 into an electrical signal.
5b. These light detection cells 16
The outputs of a and 16b (first and second detection signals) become the outputs of the optical head 10.

As the output of the optical head 10, the photodetection cells 16a, 1
The output of 6b is used for tracking deviation correction and reproduction signal.

The outputs of the photodetection cells 16a116b are supplied to amplifier circuits 20 and 21, respectively.

These amplifier circuits 20.21 are connected to the photodetection cell 16a.
, 16b is amplified and outputs a signal.゛The output of the amplifier circuit 20 is supplied to the non-inverting input terminal of a differential amplifier 22a in the subtraction circuit (calculating means) 22, and the output of the amplifier circuit 21 is supplied to the inverting input terminal of the differential amplifier 22a. Ru. The output of the differential amplifier 22a is supplied to a selector (selection means) 24 via resistors RO to R7 having different resistance values. This selector 24 selects a signal from any one of the resistors RO to R7 in response to a 3-bit (d2, dl, do) digital signal from a D-type flip-flop circuit (FF circuit) 25, which will be described later. It outputs to the gain adjustment amplifier (amplification means) 27, and is composed of a very inexpensive C-MOS analog multiplexer. This gain adjustment amplifier 27 is adjusted as shown in the table below.

The signal from the differential amplifier 22a is amplified with a gain corresponding to the resistors RO to R7 selected by the selector 24 based on the output of the FF circuit 25 and the resistor R8 in the gain adjustment amplifier 27.

For example, when resistor RO is selected by selector 24, amplification is performed with a gain of R8/RO-8/1, and when resistor R1 is selected by selector 24, R8/R1-
Amplification is performed with a gain of 8/2, and the selector 24 selects the resistor R.
2 is selected, amplification is performed with a gain of R8/R2-8/3, and when resistor R3 is selected by the selector 24, amplification is performed with a gain of R8/R3-8/4, When resistor R4 is selected by selector 24, R8/R
When amplification is performed with a gain of 4-815 and resistor R5 is selected by selector 24, when amplification is performed with a gain of R8/R5-8/6 and resistor R6 is selected by selector 24, Amplification is performed with a gain of R8/R6-8/7,
When resistor R7 is selected by selector 24, R8/
Amplification is performed with a gain of R7-8/8.

As a result, even when the detection levels of the photodetection cells 16a and 16b differ due to differences in the intensity of the laser beams, such as during recording and reproduction, a signal at a predetermined detection level can always be obtained. There is.

The output of the gain adjustment amplifier 27 is supplied to a drive circuit (drive means) 28 as a track deviation detection signal. This drive circuit 28 supplies a current corresponding to the coil 17 that drives the objective lens 11 in the horizontal direction with respect to the recording surface of the optical disc 1 in accordance with the signal supplied from the gain adjustment amplifier 27°. The objective lens 11 is driven to correct tracking deviation.

Further, a CPU (output means) 30 controls the entire system, and controls each part (not shown) using an address bus 31 and a data bus 32. Also, CPU
Reference numeral 30 indicates header information, read and write signals, and firmware supplied from an external device "a" (not shown) via an address bus, that is, input of reflected light from the optical disc 1 from recording and playback conditions to the photodetector 16. The amount of light is indirectly determined and a digital signal corresponding to the amount of incident light is outputted to the FF circuit 25 via the data bus 32.This FF circuit 25 receives a board control signal from the CPU 30. This circuit latches the digital signal supplied from the CPU 30 until the next input according to the output (3-bit digital signal d2).
, dl, do) are output to the selector 24.

The amount of light incident on the photodetector 16 depending on the recording and reproducing conditions described above changes depending on the relative speed between the optical disc 1 and the optical head 10.

In this way, even if the amount of light incident on the photodetector 16 changes, the operation is performed so that the loop gain remains constant.

Next, the operation in such a configuration will be explained.

For example, during reproduction, a (continuous) low-intensity laser beam is generated from the semiconductor laser 14, and during recording, a high current intermittently flows through the semiconductor laser 14, and an intermittent high-intensity laser beam is generated from the semiconductor laser 14 during recording. A luminous flux is generated. As a result,
The semiconductor laser 14 emits a laser beam of high intensity (recording beam) and a laser beam of low intensity (reproduction beam).

This laser beam is converted into a parallel beam by a collimator lens 13, reflected by a polarizing beam splitter 12, and then incident on an objective lens 11.
The objective lens 11 focuses the light toward the recording film of the optical disc 1 .

In this state, when recording information, pits are formed in the tracks on the optical disk 1 by irradiation with a laser beam of high intensity (recording beam light), and when reproducing information, pits are formed in the tracks of the optical disk 1 using a laser beam of low intensity. is irradiated with a laser beam (reproduction beam light). The reflected light from the optical disk 1 with respect to this reproduction beam light is converted into a parallel light beam by the objective lens 11, passes through the polarizing beam splitter 12, and passes through the projection lens 15.
irradiates onto the photodetector 16. Therefore, signals corresponding to the irradiated light are output from the photodetection cells 16a and 16b, and these signals are supplied to the amplifier circuits 20 and 21, respectively.

The tracking operation in such a state will be explained. That is, the signals from the amplifier circuits 20 and 21 are supplied to the differential amplifier 22a.

Then, the differential amplifier 22a outputs a signal obtained by taking the difference between the detection signal from the photodetection cell 16a and the detection signal from the photodetection cell 16b to the selector 24 via the resistors RO to R7, respectively. Further, the CPU 30 converts digital signals corresponding to recording and reproduction conditions, that is, digital signals corresponding to the amount of light incident on the photodetector 16 into F.
Output to F circuit 25. As a result, the FF circuit 25
A digital signal supplied from the CPU 30 via the data bus 32 is latched and output to the selector 24. Thereby, the selector 24 selects a signal from any one of the resistors RO to R7 according to the digital signal from the FF circuit 25, and outputs the selected signal to the gain adjustment amplifier 27. This gain adjustment amplifier 27 includes resistors RO to R7 selected by the selector 24 based on the output of the FF circuit 25, and the gain adjustment amplifier 2.
The differential amplifier 2 has a gain corresponding to the resistor R8 in 7.
The signal from 2a is amplified and output to the drive circuit 28 as a track detection signal. Thereby, even when the detection levels of the photodetectors 16a and 16b differ depending on the intensity of the laser beam, such as during recording and reproduction, a signal at a predetermined detection level can always be obtained.

Thereby, the drive circuit 28 supplies a predetermined current to the coil 17 according to the signal from the gain adjustment circuit 27, drives the objective lens 11 in the vertical direction, and performs tracking. As a result, the beam spot formed by the objective lens 11 can be set at the optimal position with respect to the tracking position.

Therefore, even if the detection level is different during recording and reproduction, it can be kept constant and stable control can be performed. This allows accurate tracking.

Also, when turning on the track and when jumping the track,
You can also change the loop gain.

As described above, the laser beam emitted from the semiconductor laser is focused onto the optical disk using an objective lens, the first and second signals are detected from the light reflected by the optical disk, and the detected detection signal A subtraction signal is calculated, a resistance value is selected by a selector based on a digital value corresponding to the recording/reproduction status judged by the CPU, that is, the amount of light incident on the photodetector, and the above subtraction result is selected with a gain corresponding to this resistance value. A track deviation detection signal is obtained by amplification, and the objective lens is driven by this track deviation detection signal. In other words, a digital signal is output in accordance with the change in the amount of light incident on the photodetector according to the recording and playback conditions determined by the CPU, and a gain corresponding to this digital signal is selected to control the amount of incident light. This is so that the amplified value of the track deviation detection signal does not change much due to the change. This allows stable and accurate tracking without using expensive parts.

Furthermore, the servo loop gain can be easily changed by changing the firmware.

In the above embodiment, the case of tracking control has been described, but the present invention is not limited to this and can be realized with a configuration similar to the focus control described above.

That is, if the photodetection cells 16a and 16b detect the positional deviation between the optical disk 1 and the objective lens 11, and in response to this detection, the drive circuit 28 moves the objective lens 11 in the focusing direction using the coil 18. good.

Further, although an optical disk is used as the recording medium, the present invention is not limited to this, and a laser card or the like may be used.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an information processing device that can perform stable and accurate control of the focusing means.

[Brief explanation of the drawing]

The drawing is a diagram schematically showing the configuration of an optical disk device in an embodiment of the present invention. 1... Optical disk (recording medium), 1o... Optical head (focusing means), 14... Semiconductor laser (light source), 1
1... Objective lens, 16... Photodetector (detection means)
, 16a, 16b... photodetection cell, 17.18...
Coil, 20.21...Amplification circuit, 22...Subtraction circuit (calculation means), 22a...Differential amplifier, 24...
Selector (selection means), 26... oscillator, 27...
Gain adjustment amplifier (amplification means), 28... drive circuit (drive means), RO-R8... resistor.

Claims (3)

[Claims] (1) A focusing means for focusing light emitted from a light source onto a recording medium; a detection means for detecting first and second signals from the light from the recording medium; and recording of information on the recording medium. Alternatively, an output means for outputting a digital signal corresponding to a situation such as reproduction, a selection means for selecting a gain corresponding to the digital signal outputted by the output means, and a first and second detection detected by the detection means. a calculation means for obtaining a signal for controlling the focusing means by subtracting the signal; an amplification means for amplifying the signal obtained by the calculation means with a gain selected by the selection means; and a signal amplified by the amplification means. An information processing device comprising: driving means for driving the focusing means with a signal obtained by applying a signal to the focusing means. (2) The information processing apparatus according to claim 1, wherein the control of the focusing means is focusing control or tracking control. (3) The information processing apparatus according to claim 1, wherein the selection means selects a resistor for gain adjustment.